Systems and methods of optical path protection for distributed antenna systems

Abstract

Systems and methods for optical path protection for distributed antenna systems are provided. In one embodiment, a system comprises a hub and at least one node located remotely from the hub. The hub is coupled to the node by first and second fiber paths, the first fiber path comprising an uplink fiber and a downlink fiber, the second fiber path comprising an uplink fiber and a downlink fiber. The node is coupled to the downlink fibers of the first and second fiber paths via an optical combiner, and is further coupled to the uplink fibers of the first and second fiber paths via an optical splitter. The node further monitors a signal quality of a downlink optical signal and communicates to the hub information indicative of the signal quality. The hub switches communications between the hub and the node from the first to second fiber path based on the information.

What is claimed is: 
     
       1. A first node of a distributed antenna system configured to communicate with at least one second node of the distributed antenna system, the at least one second node being remote from the first node, the first node comprising:
 first and second optical-signal ports configured to receive first and second input optical signals via first and second fiber paths, respectively; 
 an optical switch having first and second switch ports coupled to the first and second optical-signal ports, having a third switch port, and configured to couple, selectively, the first input optical signal or the second input optical signal to the third switch port in response to a quality of one of the first and second input optical signals on a single path; 
 an optical transceiver configured to receive the coupled one of the first and second input optical signals from the third switch port and to convert the coupled one of the first and second input optical signals into a first electrical signal; and 
 an interface circuit configured to convert the first electrical signal into an output RF signal. 
 
     
     
       2. The first node of  claim 1  wherein the interface circuit is configured to couple the output RF signal to an antenna. 
     
     
       3. The first node of  claim 2 , wherein:
 the interface circuit is configured to receive an input RF signal from the antenna and to convert the input RF signal into a second electrical signal; 
 the optical transceiver is configured to convert the second electrical signal into an output optical signal and to couple the output optical signal to the third switch port; and 
 the optical switch is configured, selectively, to couple the output optical signal to one of the first and second optical ports in response to the quality of one of the first and second input optical signals. 
 
     
     
       4. The first node of  claim 2 , further comprising:
 third and fourth optical-signal ports configured to provide first and second output optical signals to the at least one second node of the distributed antenna system via third and fourth fiber paths, respectively; 
 wherein the optical switch circuit includes fourth and fifth switch ports respectively coupled to the third and fourth optical-signal ports, and includes a sixth switch port; 
 wherein the interface circuit is configured to receive an input RF signal from the antenna and to convert the input RF signal into a second electrical signal; 
 the optical transceiver is configured to convert the second electrical signal into a third output optical signal and to couple the third output optical signal to the sixth switch port; and 
 the optical switch is configured, selectively, to couple the third output optical signal to one of the third and fourth optical-signal ports in response to the quality of one of the first and second input optical signals. 
 
     
     
       5. The first node of  claim 1 , further comprising a quality circuit configured:
 to determine the quality of the one of the first and second input optical signals that the optical switch is coupling to the third switch node; and 
 to toggle the optical switch to couple the other of the first and second input optical signals to the third switch node in response to the quality circuit determining that the quality of the one of the first and second input optical signals is below a quality threshold. 
 
     
     
       6. The first node of  claim 1 , further comprising:
 third and fourth optical-signal ports configured to provide first and second output optical signals to third and fourth fiber paths, respectively; 
 wherein the optical switch circuit includes fourth and fifth switch ports respectively coupled to the third and fourth optical-signal ports, and includes a sixth switch port; 
 wherein the interface circuit is configured to receive an input RF signal and to convert the input RF signal into a second electrical signal; 
 the optical transceiver is configured to convert the second electrical signal into a third output optical signal and to couple the third output optical signal to the sixth switch port; and 
 the optical switch is configured, selectively, to couple the third output optical signal to one of the third and fourth optical-signal ports in response to the quality of one of the first and second input optical signals. 
 
     
     
       7. The first node of  claim 6 , further comprising a quality circuit configured:
 to determine the quality of the one of the first and second input optical signals that the optical switch is coupling to the third switch node; and 
 to toggle the optical switch to couple the other of the first and second input optical signals to the third switch node, and to couple the third output optical signal to another one of the third and fourth optical-signal ports, in response to the quality circuit determining that the quality of the one of the first and second input optical signals is below a quality threshold. 
 
     
     
       8. A first node of a distributed antenna system, the first node comprising:
 first and second optical-signal ports configured to receive first and second input optical signals from at least one second node of the distributed antenna system via first and second fiber paths, respectively, the at least one second node being remote from the first node; 
 an optical switch having first and second switch ports coupled to the first and second optical-signal ports, having a third switch port, and configured to couple, selectively, the first input optical signal or the second input optical signal to the third switch port in response to a quality of one of the first and second input optical signals determined in response to a measurement taken at a single circuit; 
 an optical transceiver configured to receive the coupled one of the first and second input optical signals from the third switch port and to convert the coupled one of the first and second input optical signals into a first electrical signal; and 
 an interface circuit configured to convert the first electrical signal into an output RF signal. 
 
     
     
       9. A method, comprising:
 receiving, via first and second optical paths, first and second input optical signals at first and second optical-signal ports, respectively, of a first node of a distributed antenna system; 
 determining a quality of one of the first and second input optical signals along one and only one signal path; 
 coupling, selectively, the first input optical signal or the second input optical signal to an optical transceiver in response to the determined quality of the one of the first and second input optical signals; 
 converting, with the optical transceiver, the coupled one of the first and second input optical signals into a first electrical signal; and 
 converting the first electrical signal into an output RF signal. 
 
     
     
       10. The method of  claim 9  wherein receiving the first and second input optical signals includes receiving the first and second optical signals from at least one second node of the distributed antenna system, the at least one second node located remote from the first node. 
     
     
       11. The method of  claim 10 , further comprising:
 receiving, from an antenna, an input RF signal at the first node; 
 converting the input RF signal into a second electrical signal; 
 converting, with the optical transceiver, the second electrical signal into an output optical signal; and 
 coupling, selectively and in response to the determined quality of one of the first and second input optical signals, the output optical signal to the at least one second node via one of third and fourth fiber paths respectively coupled to third and fourth optical-signal ports of the first node. 
 
     
     
       12. The method of  claim 9 , further comprising:
 coupling the output RF signal to an antenna; and 
 radiating a transmission signal with the antenna in response to the output RF signal. 
 
     
     
       13. The method of  claim 9 , further comprising:
 receiving, at the first node, an input RF signal from an antenna; 
 converting the input RF signal into a second electrical signal; 
 converting, with the optical transceiver, the second electrical signal into an output optical signal; 
 coupling, selectively, the output optical signal to one of the first and second optical ports in response to the quality of one of the first and second input optical signals. 
 
     
     
       14. The method of  claim 9 , further comprising:
 determining the quality of the one of the first and second input optical signals coupled to the optical transceiver; and 
 coupling the other of the first and second input optical signals to the optical transceiver in response to determining that the quality of the one of the first and second input optical signals is below a quality threshold. 
 
     
     
       15. The method of  claim 9 , further comprising:
 receiving an input RF signal at the first node; 
 converting the input RF signal into a second electrical signal; 
 converting, with the optical transceiver, the second electrical signal into an output optical signal; and 
 coupling, selectively and in response to the quality of one of the first and second input optical signals, the output optical signal to one of third and fourth fiber paths respectively coupled to third and fourth optical-signal ports of the first node. 
 
     
     
       16. The method of  claim 15 , further comprising
 coupling the other of the first and second input optical signals to the optical transceiver, and coupling the output optical signal to another one of the third and fourth fiber paths, in response to determining that the quality of the one of the first and second input optical signals is below a quality threshold. 
 
     
     
       17. A distributed antenna system, comprising:
 at least one first node; 
 a second node configured to communicate with, and being remote from, the at least one first node, the second node comprising
 first and second optical-signal ports configured to receive first and second input optical signals via first and second fiber paths, respectively, 
 an optical switch having first and second switch ports coupled to the first and second optical-signal ports, having a third switch port, and configured to couple, selectively, the first input optical signal or the second input optical signal to the third switch port in response to a quality of a single branch of one of the first and second input optical signals, 
 an optical transceiver configured to receive the coupled one of the first and second input optical signals from the third switch port and to convert the coupled one of the first and second input optical signals into an electrical signal, and 
 an interface circuit configured to convert the electrical signal into an output RF signal. 
 
 
     
     
       18. The distributed antenna system of  claim 17  wherein:
 the at least one first node includes at least one remote node; and 
 the second node includes a hub. 
 
     
     
       19. A non-transitory computer-readable medium storing instructions that, when executed by at least one computing circuit, cause the at least one computing circuit, or at least one other circuit responsive to the at least one computing circuit:
 to receive, via first and second optical paths, first and second input optical signals at first and second optical-signal ports, respectively, of a first node of a distributed antenna system; 
 to couple, selectively, the first input optical signal or the second input optical signal to an optical transceiver in response to the quality of one of the first and second input optical signals at a location along a single path; 
 to convert, with the optical transceiver, the coupled one of the first and second input optical signals into an electrical signal; and 
 to convert the electrical signal into an output RF signal. 
 
     
     
       20. A distributed antenna system, comprising:
 a first node; 
 a second node coupled to the first node via a first cable and a second cable; 
 a third node coupled to the second node via a third cable and a fourth cable; 
 wherein the first node is configured to transmit a first signal over the first cable; and
 wherein the second node is configured to couple the first signal from the first cable to the third cable such that the first signal from the first node can be sent over the first cable and third cable to the third node; 
 
 wherein the third node is configured to transmit a second signal over the fourth cable, and wherein the second node is configured to couple the second signal from the fourth cable to the second cable such that the second signal from the third node can be sent over the fourth cable and the second cable to the first node; 
 wherein the first node is configured to obtain information indicative of a signal quality of the first signal from a single path, and to switch from the first cable to the second cable based on the signal quality. 
 
     
     
       21. A method comprising:
 sending a first signal from a first node to a second node on a first wired link; 
 at the second node, coupling the first signal from the first wired link to a third wired link; 
 receiving the first signal at a third node on the third wired link; 
 along one and only one signal path of the first node, obtaining information indicative of a signal quality of the first signal as the first signal propagates along the one and only one signal path; 
 at the first node, switching from the first wired link to a second wired link based on the signal quality; 
 sending a second signal from the third node to the second node on a fourth wired link; 
 at the second node, coupling the second signal from the fourth wired link to the second wired link; and 
 receiving the second signal at the first node.